A fuel battery module mounted on a fuel battery system includes a plurality of cell stacks, the cell stack being an aggregate of fuel battery cells. The cell stack has a large number of fuel battery cells arranged and connected in series, thereby to make a voltage to be output high.
Here, Patent Literatures 1 and 2 propose structures in which a plurality of battery cell units provided with a fuel battery cell on a surface of a substrate tube is connected in series. Patent Literature 1 describes a structure provided with a cylindrical joining member having an outer diameter smaller than an inner diameter of the substrate tube and arranged inside the substrate tube, and an adhesive member having the same solid particles as the substrate tube between the joining member and the substrate tube, and connects two substrate tubes. Patent Literature 2 describes a structure that includes unit cells (battery cell units), and a support member that penetrates hollow portions of the unit cells to connect the unit cells in a longitudinal direction.